T. Keith Philips

Department of Entomology, Museum of Biological Diversity The Ohio State University, 1315 Kinnear Road, Columbus, OH 43212

Current Address: Biology, Western Kentucky University, Bowling Green, KY 42101

While going through a sample from a flight intercept trap set in Belize, I came across a specimen of Micromalthus debilis LeConte, apparently the first record from Central America. This species, belonging to the monotypic family Micromalthidae, is recorded as native to eastern North America. While M. debilis might be common and is known from several states (Downie & Arnett 1996), individual collecting events appear rare.

In addition to being classified in a monotypic family, this species has an intriguing biology. Larvae develop in moist decaying hardwoods and can go through several stages and shapes in their development, appearing as caraboid, cerambycoid, and curculionoid larval types. The complicated lifecycle involves paedogenesis and several types of parthenogenesis (thelytoky, amphitoky, and arrhenotoky) (for details see Barber 1913a, b; Pringle 1938; Scott 1936, 1938, 1941).

The classification of this species has undergone much discussion and controversy. Although Downie & Arnett (1996) place the family within the Polyphaga based on several shared adult features with the Cantharoidea (or Elateroidea sensu Lawrence & Newton [1995]), overwhelming evidence from larval, wing, and male genitalic characters indicates that placement of the family within the Archostemata is correct (Lawrence & Newton 1995).

It is apparent that M. debilis was once much more widespread. Fossil larval records from amber are known from Lebanon (Cretaceous), the Baltic (Oligocene), the Dominican Republic (M. Lvie, pers. comm.) and Chiapas, Mexico (late Oligocene or early Miocene) (Lawrence & Newton 1995; Rozen 1971). Currently, Micromalthus debilis is considered native only to the eastern United States. Other North American records are British Columbia and New Mexico (Borror et al. 1986). More distant and overseas localities are South Africa (Scholtz & Holm 1985), Cuba, Brazil, Hong Kong, and Hawaii (Lawrence 1982). Arnett's (1968) record from Europe, based on Silvestri (1941), is in error, as Silvestri only stated that M. debilis should be found in Europe due to the import of large amounts of timber from the New World.

Most of these records (outside the eastern U.S.) undoubtedly are the result of introductions via the spread of larvae in dead wood (Lawrence & Newton 1995). But it can sometimes be difficult to ascertain whether a species is native or introduced, as Whitehead and Wheeler (1990) pointed out.

The Belize specimen was collected in an area of relatively pristine forest (Orange Walk District, Rio Bravo Conservation Area, Well Trail near Research Station, 16-18.IV.1995, flight intercept trap, P. W. Kovarik), distant from any commercial center. This record appears to represent a disjunction, but the fossil record shows that the species was once present in nearby southern Mexico. Individuals are only rarely collected, and the sampling effort for small beetles in southern Mexico and Belize has been minimal, especially compared to that in eastern North America. Also, one of the known hosts, Quercus, is present in the Rio Bravo Conservation Area (P. Kovarik, personal communication). Hence, M. debilis might have a much more widespread native distribution than previously thought, and this Belize record might not be the result of an introduction. It is even possible, though perhaps less likely, that the Cuban record represents a natural distribution in the West Indies. Regardless of the factors resulting in the present distribution, it remains to be discovered how widespread this beetle family may actually be. I thank Alfred Wheeler and one anonymous reviewer for their comments.